How to propagate or sow Catalpa?

Catalpa is a handsome shade tree prized for its large heart-shaped leaves, its clusters of white flowers speckled with reddish-brown in summer, and its long pod-like fruits resembling beans. It is also notable for its rapid growth and its ability to provide cool shade where it is pleasant to shelter from strong summer sun. Very hardy (down to -30°C), easy to grow, it establishes in most medium to large gardens, sheltered from strong winds as its wood is brittle. Multiplication is by propagation by cuttings or by sowing. Discover how to germinate Catalpa seeds or take cuttings to obtain new young plants!

By propagation by cuttings

Propagation by cuttings produces new young plants identical to mother plant. However, this is a fairly delicate method to multiply Catalpa. Results are rather unpredictable.

When to take cuttings from Catalpa ?

Propagation by cuttings of Catalpa is carried out from May to July (herbaceous cuttings), when tree is in full period of growth.

How to take cuttings from Catalpa ?

Select stems still green, healthy and vigorous, about 15–20 cm long
Cut just below an eye with a clean, sharp pruning shear
Remove leaves from lower third and leave only one or two pairs of leaves at top of stem
Optionally dip base of stems in rooting hormone to stimulate root growth
Fill a pot with a mix of potting compost and sand or with special seed compost
Make a small hole using a pencil or stick
Place cutting in hole so it is inserted to two-thirds of its length
Firm soil well all around
Water generously
Keep substrate slightly moist and cover cuttings with a plastic bag or a cut plastic bottle to maintain humid environment (covered propagation)
Place cuttings in a bright spot, out of direct sun
Ventilate regularly to avoid development of fungal diseases
Roots will develop in 4 to 6 weeks
Pot on sufficiently developed, well-rooted young plants into larger pots in autumn
Wait until following spring to transplant into garden in final position

To find out more: « Propagation by cuttings: everything you need to know about different techniques and our advice »

Materials required

A pruning shear clean and sharp
Pots
Potting compost for sowing or soil mixed half and half with coarse sand to obtain draining substrate
Pencil
Cutting hormone (facultative)
Plastic bag or a cut plastic bottle

By sowing

Sowing Catalpa is child's play! After flowering, this tree produces very decorative long brown pods reminiscent of beans. You can harvest them to collect the seeds they contain and sow them.

When to sow Catalpa ?

Catalpa seeds can be sown directly in autumn.

How to sow Catalpa ?

Catalpa seeds are generally ready to harvest at end of summer or early autumn. Seed pods should be dry and beginning to open. This is sign that seeds inside are ripe.

Soak seeds in water for a few hours before sowing to promote germination
Fill pots with a mix of potting compost and sand, or with special seed compost
Sow seeds about 6 mm deep in pots and cover with a thin layer of compost
Water gently
Place pots under a cold frame
Keep substrate slightly moist (but not waterlogged) using a mister
Seeds germinate within a few weeks
When seedlings are large enough to handle, pot them on into individual pots
Plant out in ground in spring choosing a sunny or partially shaded spot